In a data communication network, network elements may comprise internetworking infrastructure elements such as routers, switches, other internetworking devices, or components thereof, or end stations such as printers or general purpose computers that are typically, but not always, located at the edge of a given network. Some of the devices may be owned or operated by an Internet Service Provider (ISP) and are sometimes referred to as Service Provider Equipment (SPE). Other devices may be owned or operated by the customer using a service provided by an ISP and are sometimes referred to as Customer Equipment (CE).
In addition to network elements, a network may comprise one or more Business Elements (BE). A Business Element is a construction or organization of certain network elements and their properties into a logical entity. In some cases, the logical entity is intended to provide the ability to track the network elements in a way that makes sense from a business perspective. As an example, a virtual private network (VPN) may be viewed as a business element that represents a set of interconnected sites that appear to form a single private network over a public network. Business elements may also include virtualized components or devices in a network. The virtualized components and devices may perform operations typically associated with physical components and devices. However, the virtualized components and devices may in fact be implemented by a collection of one or more network elements which are the physical devices assisting in the operation.
In many cases customers wish to interconnect the various network and business elements that comprise their networks so that information can be transferred from one to another. However, it may not always be feasible for a customer to directly connect all the elements of their network. For example, the different segments of the customer's network may be geographically separated and it would be too expensive to run a direct line from one to another. Thus, the customer may have to resort to utilizing a service provider network in order to interconnect the remote regions of the customer's network.
However, the customer may want the different segments of their network to be able to communicate as though they were directly wired together. As a result, some service provider networks support Virtual Connections. A Virtual Connection may be defined as an association of two or more User Network Interfaces (UNIs) with connectivity between them. The UNI is the point of demarcation between the customer's network and the network of the service provider. The components which the Virtual Connection connects are sometimes referred to as the subscribers of the Virtual Connection. The service provider network may endeavor to ensure that data originating from one subscriber is only delivered to other subscribers of the same Virtual Connection. In this fashion, a Virtual Connection may mimic a direct line between the subscribers. A service provider network may implement a Virtual Connection by means of network and business elements which define rules indicating how traffic should be routed through the network.
One particular type of Virtual Connection is an Ethernet Virtual Connection (EVC). An example of which is described by a paper published by the Metro Ethernet Forum (MEF) entitled “Metro Ethernet Services—a Technical Overview,” 2006, the entire contents of which are hereby incorporated by reference for all purposes as if fully set forth herein. An EVC is a Virtual Connection that attempts to emulate an Ethernet hub or a direct Ethernet line. In an EVC, the traffic sent to and from the customer equipment consists of Ethernet frames and the EVC attempts to emulate the properties of an Ethernet Connection for traffic sent over the service provider network. The service provider network through which an EVC passes is sometimes referred to as a Metro Ethernet Network (MEN).
In some cases, a Virtual Connection may pass through network segments which implement Multi Protocol Label Switching (MPLS). MPLS is a mechanism in high-performance telecommunications networks that directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table. The labels identify virtual links between distant nodes rather than endpoints. MPLS can potentially encapsulate packets of many different network protocols. Networks which implement MPLS may associate links in the network with particular VLANs and use VLAN tags incorporated into the traffic as the labels MPLS uses to route the traffic.